What is the primary function of Power Nap during sleep mode?

The primary function of Power Nap during sleep mode is to back up data and check for updates. Power Nap allows the Mac to perform certain tasks while it is in a low-power sleep state. This feature enables the system to stay in touch with the latest information by allowing it to check for email, calendar updates, and software updates without fully waking up. It ensures that when you wake your Mac, it is refreshed with the most current information and that your data is backed up if you have Time Machine configured.

This functionality enhances user experience by minimizing downtime and keeping services updated while saving energy, which is particularly useful for portable devices that rely on battery life.